Throughout recent years in the lighting industry there has been a definite trend and development in the field known as "track lighting". This involves the use of a track which is either recessed into a ceiling surface or suspended below such a surface and extends across the greater or entire length of a room. The track usually includes a longitudinal central recess in which electrical conductors are insulatingly positioned. Special connector members are designed which may be inserted into the recess in the track, usually turned 90 degrees to lock them in place, and in doing so make electrical contact with the conductors. The connector or adapter may be coupled to any of a variety of types of lighting fixtures.
The principal advantage of track lighting is that lighting fixtures may be located at any place along their length and after being installed, may be removed and replaced with different lighting fixtures or may be moved along the length of the track to the desired location. This type of system has been particularly useful in commercial, retail and window display applications where the points of desired lighting and direction of lighting may change as displays change, and track lighting affords this high degree of flexibility. Also the track itself is not obstrusive into the scene and in fact can be quite attractive. It is usually formed of anodized aluminum formed by extrusion.
Representative patents showing track lighting systems are: U.S. Pat. Nos.
______________________________________ 2,977,566 M. Neumann et al Mar. 28, 1961 3,894,781 A. C. Donato Jul. 15, 1975 4,289,365 H. J. Rutgers Sep. 15, 1981 3,737,834 J. Contrallo June 5, 1973 and 3,832,503 R. B. Crane Aug. 27, 1974. ______________________________________
More recently track lighting systems have been applied to residential applications affording the same degree of flexibility. It has been found however that in both commercial and residential applications, there is a desire for a relatively fixed location for the fixtures after they are installed, but a degree of flexibility in the lighting effects achieved. This may be accomplished in part by the use of dimmer switch controls which allow the user to control the light intensity on the scene. More recently, it has been the desire of commercial and residential users to have more than one circuit in a single track light system allowing two independent controls for two different sets of lights on a single track. Either or both may be dimmer controlled for additional flexibility. An auxiliary advantage of having dual circuits is that the danger of overload of a single circuit is reduced by the presence of two circuits, and directions to use part of the lighting fixtures on one circuit and part on the other circuit.
Accomplishing these ends in a single track, which is reliable, safe and has no danger of misconnection or short circuiting, has heretofore escaped lighting designers.